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    <script>
        var threeSum = function (nums) {
            let ans = [];
            const len = nums.length;
            if (nums == null || len < 3) return ans;
            nums.sort((a, b) => a - b); // 排序
            for (let i = 0; i < len; i++) {
                if (nums[i] > 0) break; // 如果当前数字大于0，则三数之和一定大于0，所以结束循环
                if (i > 0 && nums[i] == nums[i - 1]) continue; // 去重
                let L = i + 1;
                let R = len - 1;
                while (L < R) {
                    const sum = nums[i] + nums[L] + nums[R];
                    if (sum == 0) {
                        ans.push([nums[i], nums[L], nums[R]]);
                        while (L < R && nums[L] == nums[L + 1]) L++; // 去重
                        while (L < R && nums[R] == nums[R - 1]) R--; // 去重
                        L++;
                        R--;
                    }
                    else if (sum < 0) L++;
                    else if (sum > 0) R--;
                }
            }
            return ans;
        };
        console.log(threeSum([-1, 0, 1, 2, -1, -4]))
    </script>
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